JP2995945B2 - Packaging bag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging bag suitable for use in foods and the like which are susceptible to oxygen oxidation and having a capability of absorbing oxygen inside a bag and a capability of suppressing oxygen intrusion from outside the bag.

[0002]

2. Description of the Related Art Foods susceptible to oxygen oxidation, such as (a) potato chips, rice crackers, cookies, shrimp, instant ramen, cutlet, peanuts, fly beans, nuts, oysters, fish meal, kneaded tofu, powdered milk,
Low-moisture foods containing fats and oils such as cake mix and buckwheat flour;
(B) Fish, fish paste products (kamaboko, chikuwa, etc.), meat (cow, horse, sheep, whale, pork, etc.), wakame, wasabi, raw noodles, Japanese confectionery (buns, dorayaki, middle, amanatto, etc.), western confectionery (Castella, baumkuchen, fruit cake), high-moisture foods such as sweet chestnut, mochi, (c) salami, ham, sausage,
When storing high-moisture-based foods such as butter, cheese, margarine, roasted chicken, hamburger, Frankfurt, western confectionery, cereals, etc. containing oils and fats in packaging bags and storing them, trace amounts of oxygen present in the packaging bags and foods It has been pointed out that the contents are oxidized by oxygen entering from the outside of the bag during the storage period and the taste changes during the storage period.

In order to solve this problem, packaging with a film having a high oxygen barrier property such as an aluminum vapor-deposited film, a polyvinyl alcohol-based film, a nylon-based film, a polyvinylidene chloride-coated film, and a polyester-based film, vacuum packing, nitrogen replacement, oxygen replacement, etc. Countermeasures have been taken through the use of absorbents. Regarding the use of this oxygen absorber, it is necessary to put it in a breathable packaging bag (Japanese Patent Publication No. 57-57).
No. 31449, Utility Model Registration No. 1783423,
(U.S. Pat. No. 4,536,409), embedding in a thermoplastic resin (JP-A-1-308781, JP-A-1-315438), and lamination with a breathable film (JP-A-1-308781). Showa 55-44344, 55-1074
No. 65, 60-183373).

[0004] However, these conventional methods have problems such as insufficient oxygen removal from the package contents and high cost. That is, even if an oxygen barrier film is used, it has a slight oxygen permeability, so that even if a vacuum packing or nitrogen replacement method is used, oxygen cannot be completely removed, and long-term storage cannot be performed. In addition, the vacuum packing and the nitrogen replacement method are expensive only due to the complicated steps, and therefore can be applied only to high-end products. Applying an oxygen absorber is a simple method, but simply putting it in a bag will cause the oxygen absorber to absorb moisture, etc., and its oxygen absorption performance will be immediately reduced. There were problems such as being difficult to apply to the contents, the possibility of accidental eating, and the inability to prevent oxygen from entering from outside the packaging bag.

[0005] In order to solve the above-mentioned problems, the present invention has a sufficient oxygen absorbing ability in a bag and maintains the high oxygen absorbing ability for contents such as a high moisture content for a long period of time. It is an object of the present invention to provide a packaging bag that can be manufactured at a low cost and that can efficiently suppress oxygen intrusion from outside the bag.

[0006]

In order to achieve this object, a packaging bag according to the present invention comprises at least a part of a bag, an oxygen absorber layer in which an oxygen absorbent is embedded in a resin, and the oxygen absorbing layer. An oxygen-permeable layer having an asymmetric porous layer in which a dense thin film layer is formed on the inside of the bag in the thickness direction, which is located on the inside of the bag of the body layer,
It is composed of a laminate comprising an oxygen-absorbing film layer located on the outside of the bag of the oxygen-absorbing layer.

In the structure of the present invention, the oxygen absorber in which the oxygen absorbent is embedded in the resin absorbs oxygen entering from inside and outside of the packaging bag, and the oxygen permeable layer having the asymmetric porous layer is formed from the contents. The oxygen barrier film has a function of shielding the oxygen absorber and preventing oxygen from entering from the outside. Since the laminated body composed of these constituent elements constitutes at least a part of the packaging bag, not only oxygen absorption inside the packaging bag but also intrusion of oxygen from the outside can be effectively prevented, so that the contents can be stored. The period is dramatically improved.
In order to improve the sealing property of the packaging bag, a known sealing film can be laminated on part or all of the inner surface (on the oxygen permeable layer side).

In the present invention, the “asymmetric porous layer”
This is a layer necessary to make it possible to shield the oxygen absorber from the contents while maintaining sufficient oxygen permeability. In the present invention, the asymmetric porous layer refers to a layer comprising a very thin dense layer on one side of a flat membrane sheet and a porous layer supporting the dense layer. Since the dense thin film layer has Angstrom level holes necessary for oxygen transmission,
The shielding effect against contents, especially moisture, etc. is much larger than that of the conventional porous membrane, and the thickness of the dense layer is thin, so that the oxygen permeability can be made much higher than that of the conventional sheet. In other words, a sufficiently high oxygen permeability can be exhibited while achieving a sufficiently high content shielding effect. This dense thin film layer is supported by a porous layer having high oxygen permeability. Further, when there is a possibility that a sufficient shielding effect cannot be expected only with the asymmetric porous layer, as in the case where the pressure in the packaging bag becomes high, or in the case of aqueous and / or oily contents, etc. By further providing an oxygen-permeable homogeneous thin film layer on the thin-film layer, it is possible to further improve the shielding effect without significantly lowering the oxygen permeability. The oxygen-permeable layer having an asymmetric porous layer may be in the form of a so-called “oxygen-permeable composite membrane” supported by a woven or nonwoven fabric layer.

[0009] The "oxygen absorber layer in which the oxygen absorbent is embedded in the resin" in the present invention is a layer that absorbs oxygen in the packaging bag and in the contents, and the oxygen absorber is actually used in the package. It is a layer necessary for improving storage stability and maintaining shape until used as a part. As the oxygen absorbent in the present invention, those that exhibit oxygen absorbing ability under high humidity can be preferably used. However, such an oxygen absorbent itself is deactivated when activated to some extent by moisture in the air. Therefore, by embedding the oxygen absorbent in a resin that allows moisture and oxygen to pass under high humidity without passing through moisture in a normal atmosphere, it is possible to prevent deactivation of the oxygen absorbent until it is actually used. . Therefore, by using this oxygen absorber layer, the storage stability until it is actually used can be improved, and the form as a laminate can be easily maintained.

[0010] The "oxygen barrier film layer" in the present invention is a layer that prevents oxygen from entering from outside the packaging bag, and also directs most of the oxygen absorbing capacity of the oxygen absorber layer to absorb oxygen in the packaging bag. This is a layer necessary for efficiently reducing the oxygen concentration in the packaging bag and maintaining the low oxygen concentration state. In addition, during the storage period of the laminated body of the present invention before use, the oxygen absorbing layer is not directly exposed to the atmosphere due to the presence of the oxygen barrier film layer, so that the oxygen absorbing performance of the oxygen absorbing layer is Is prevented from decreasing.

Hereinafter, the packaging bag of the present invention, particularly each part of the laminate, will be described in more detail. (1) Asymmetric porous layer The asymmetric porous layer is composed of a very thin dense layer on one side of a flat membrane sheet and a porous layer supporting the dense layer. The dense layer existing on one side of the layer is formed as a very thin layer having pores of 0.0005 to 0.5 μm and a thickness of about several μm. Since the asymmetric porous layer has a thin dense layer and the subsequent porous layer has high porosity, the gas or water vapor permeation rate is very high. As a preferred embodiment of the present asymmetric porous layer, from the viewpoint of achieving both the effect of shielding moisture and the like and the oxygen transmission rate, and from the viewpoint of forming the oxygen-permeable homogeneous thin film layer when the oxygen-permeable homogeneous thin film layer is provided. The preferred pore diameter of the dense thin film layer is 0.001 to 0.1 μm. The total thickness of the asymmetric porous layer is generally 1 to have a practical mechanical strength and to obtain a sufficient gas permeation rate.
It is 300 μm, preferably 10 to 100 μm. Although it is possible to use a film structure having a symmetric structure in the film thickness direction, an asymmetric porous structure is necessary to achieve both a shielding effect and an oxygen permeation rate. By doing so, the gas permeation resistance can be reduced. The porosity of the entire membrane is
It can be arbitrarily selected according to the purpose, but generally 10 to 90
%. If the porosity is high, the gas permeation speed is high, and if the porosity is low, the durability is excellent. However, in the present invention, the porosity is 70 to 85% in the sense of having both of these characteristics. A preferred example is an asymmetric porous layer. The asymmetric porous layer may be formed by a known method, for example, a wet method, a dry-wet method, a melting method,
A film formed by a stretching method or the like is appropriately used. Examples of the material forming the asymmetric porous layer include aromatic polysulfone-based materials such as polysulfone, polyether sulfone, polyphenylene sulfide sulfone, and polyphenylene sulfone; cellulose-based materials such as cellulose acetate, ethyl cellulose, and cellulose; polyacrylonitrile, polypropylene, and polyethylene. Polyolefin-based materials such as polyvinylidene fluoride, fluorine-containing polymer-based materials such as polytetrafluoroethylene, polyamide-based materials or polyimide-based materials and polyurethane-based materials can be used. And an aromatic polysulfone-based material is preferably used because the pore size is easily controlled. The gas permeability of this porous layer is 10 to 10000 in air permeation speed.
[M ³ / m ² · hr · atm] is preferable.

(2) Layer made of woven or non-woven fabric A base layer made of woven or non-woven fabric is provided as a support layer for supporting the asymmetric type porous layer, and oxygen is transmitted between the asymmetric type porous layer and this support layer. The layer may be in the form of a so-called “oxygen-permeable composite membrane”. The base layer made of the woven or nonwoven fabric preferably has sufficient air permeability and good mechanical strength. Examples of those having such properties include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyamides such as nylon, and known woven or nonwoven fabrics mainly containing natural fibers and the like. The air permeability of the woven or nonwoven fabric is not particularly limited as long as oxygen transmitted through the asymmetric porous layer does not cause a large resistance until it reaches the oxygen absorber layer. As the air permeability, for example, 0.01 to 100 [ml /
cm ² · sec], and in consideration of the film forming properties of the asymmetric porous layer and the performance of the oxygen absorber layer having a composite structure, 0.1 to 10 ml / cm ² · sec.
c) is particularly preferred. Further, the thickness is particularly preferably 50 to 300 μm from the viewpoint of the supporting strength. In the case of a nonwoven fabric, the basis weight corresponding to this performance is 10 to 20
A range of 0 g / cm ² can be mentioned as a suitable amount.

(3) Oxygen-permeable homogeneous thin film layer An oxygen-permeable homogeneous thin film layer may be further provided on the oxygen-permeable layer inside the container. This oxygen permeable homogeneous thin film layer
It is a layer that more reliably prevents the permeation of liquid contents such as water and oil, and allows oxygen and water vapor to permeate. The oxygen permeability of the homogeneous oxygen-permeable thin film layer is such that when the oxygen permeability coefficient P _o2 is used, _{Po 2} is 1 × 10 ⁻¹⁰ [cm ³ (STP) · cm /
cm ² · sec · cmHg] (= volume / film thickness / film area / time / pressure of gas converted to standard state) or more, and more preferably 1 × 10 ⁻⁹ [cm ³ (STP) · cm /
cm ² · sec · cmHg] or more. The water vapor permeability is unconditionally determined because it depends on the temperature and pressure in the bag, the contents of the bag, and the characteristics of the oxygen absorbent. However, as a rough guide, 0.5 [g / m ² · atm · 2
4 hr] or more can be mentioned as a preferable example.

As a polymer satisfying the above range, for example,
Polyorganosiloxanes such as polydimethylsiloxane, polymethylphenylsiloxane, cross-linked polymer of polydimethylsiloxane derivative, polyorganosiloxane /
Polyorganosiloxane copolymers such as polystyrene copolymer, polyorganosiloxane / polycarbonate copolymer, polyorganosiloxane / polysulfone copolymer, poly (4-methylpentene-1), polyethylene / propylene copolymer, poly (4-methylpentene-
1) crosslinked polymer, polyolefins such as poly (di-tert-butyl fumarate), poly (2,6-dimethyl-1,4-phenylene oxide) and silyl-modified poly (2,6-dimethyl-1, Polyphenylene oxides such as 4-phenylene oxide), substituted acetylene polymers such as poly (trimethylsilylpropyne) and poly (tert-butylacetylene), celluloses such as ethylcellulose, and poly (bisethoxyphosphazene)
And polyorganophosphazenes.

In order to form a pinhole-free homogeneous oxygen-permeable thin film layer that enables high oxygen permeability, a polyorganosiloxane crosslinked polymer or poly (4-methylpentene-1) is used.
The crosslinked polymer of the above can be mentioned as a preferable example.
Examples of the crosslinkable modified polyorganosiloxane include silanol-modified polyorganosiloxanes represented by the following chemical formulas (1) and (2).

[0016]

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[0017]

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In the above formulas (1) and (2), R 1 and R 2 are methyl, ethyl, propyl or phenyl, and R 3 is
A methyl group, an ethyl group or a propyl group, and R4 has 2 carbon atoms.
Represents an alkyl group of up to 15 or a compound represented by the following formula 3. P + p ′ = 3 and p is an integer of 1 to 3, 0.001 ≦ m / (m + n) ≦ 0.20,
n + m represents an integer of 50 to 3000.

[0019]

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These compounds include silane crosslinking agents having high reactivity with silanol groups such as polyfunctional acetoxy silanes, oxime silanes, alkoxy silanes, alkenyloxy silanes, amide silanes, amino silanes, and the above silane crosslinking agents. Can be cross-linked by a siloxane cross-linking agent which is a hydrolyzate of Although the number of the functional groups is not particularly limited, tetrafunctional or more is preferred in consideration of the high reactivity and the ability to form a thin film on the microporous support and the strength of the thin film. Specific examples include tetraacetoxysilane, tetradimethyloximesilane, ethylorthosilicate, propylorthosilicate, tetrakisisopropenixisilane, ethylpolysilicate, pentadimethyloximesiloxane, hexadimethyloximesiloxane, and hexaacetoxysiloxane. The reaction may include a catalyst to increase the reaction rate, such as dibutyltin acetate, dibutyltin octoate, and the like.

Examples of other polydimethylsiloxane derivatives include amino-modified polydimethylsiloxane represented by the following chemical formulas (4) and (5).

[0022]

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[0023]

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[0024] These compounds are obtained by converting a polydimethylsiloxane derivative into a polyfunctional compound having two or more functional groups such as acid chloride, acid anhydride, isocyanate, thioisocyanate, sulfonyl chloride, epoxy, aldehyde and active halogen in the molecule. It can be a crosslinked polymer.
Among them, acid chlorides, isocyanate compounds, and aldehyde compounds have high reactivity and are particularly preferable. For example, isophthalic acid dichloride, terephthalic acid dichloride, trimesic acid chloride, fumaric acid dichloride, tolylene-2,
4-diisocyanate, diphenylmethane-4,4,-
Examples include diisocyanate, glutaraldehyde, and phthalaldehyde.

Examples of the crosslinked poly (4-methylpentene-1) include self-crosslinked trimethoxyvinylsilane-grafted poly (4-methylpentene-1). However, as long as the oxygen permeability coefficient substantially satisfies the above range, it is possible to use without being limited to these. Further, the polymer forming the oxygen-permeable homogeneous thin film layer may be added with another polymer as long as the permeability of the thin film layer is not impaired, and a mixing method using two or more kinds of the above polymers, There is a lamination method and the like.

As the method for forming the oxygen-permeable homogeneous thin film layer, any method such as a polymer coating method, an interfacial polymerization method of monomers, a method of crosslinking a crosslinkable polymer after coating, and a plasma polymerization method can be used. However, when the thickness of the thin film is too small, the mechanical strength of the thin film layer decreases, and when the thickness is too large, the oxygen transmission rate decreases. 05
Suitably, it is で 1 μm.

(4) Oxygen-permeable composite membrane A laminate comprising an asymmetric porous layer and a woven or non-woven fabric support layer is referred to as an "oxygen-permeable composite membrane" in the present invention. The oxygen-permeable composite membrane may further be provided with an oxygen-permeable homogeneous thin film layer on the asymmetric porous layer. The oxygen-permeable composite membrane is a composite membrane composed of a support layer made of a woven or non-woven fabric and an asymmetric porous layer provided on the support layer, or a support layer or an asymmetric type provided on the support layer. Although no problem as long as the composite film structure comprising a porous layer and the oxygen permeable homogenous thin layer provided on the non-symmetric porous layer, 0.1 is the oxygen permeation rate Q _O2
Those of 50 [m ³ / m ² · hr · atm] are preferable,
More preferably, 0.5 to 15 [m ³ / m ² · hr · at
m]. If the oxygen permeation rate is lower than the above range, the oxygen absorption rate of the oxygen absorber decreases, which is not preferable.If the oxygen permeation rate exceeds the above range, the oxygen permeable composite membrane is contacted with another substance or the like. However, it is not preferable because it is easily damaged. For water vapor permeability,
1.0 g / m ² · at to activate the oxygen absorber
m · 24 hr] or more. In particular, in the case of foods and beverages which are easily oxidized, 10 g / m ² · atm
.24 hr] or more, more preferably 40 [g / m ² · a]
tm.24 hr] or more.

In the oxygen-permeable composite thin film having the oxygen-permeable homogeneous thin film layer, the oxygen-permeable homogeneous thin film layer is preferably a pinhole-less homogeneous layer.
The homogeneity is used as an index for the oxygen / nitrogen transmission rate ratio α (= Q
_O2 / Q _N2 ). When the specific oxygen / nitrogen transmission rate ratio of the material forming the oxygen-permeable homogeneous thin film layer is α ^* , α of the oxygen-permeable composite membrane is preferably 0.5α ^{* to} 2.0α ^* , Preferably 0.
8α ^{* to} 1.5α ^* . When α of the oxygen-permeable composite membrane is lower than the above range, pinholes are present in the oxygen-permeable homogeneous thin film layer, which is not preferable. When α exceeds the above range, the oxygen-permeable homogeneous thin film layer is porous. The layer may be impregnated, which undesirably lowers the oxygen transmission rate of the oxygen-permeable composite membrane.

(5) Resin for embedding the oxygen absorbent For example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, vinyl chloride, isoprene, butadiene, chloroprene, urethane or acrylic polymer is also used. It is possible. There is no particular limitation as long as it can hold the oxygen absorbent. However, considering oxygen permeability and water vapor permeability, silicone resin can be mentioned as the most preferable example. It is desirable that the embedding resin is packed as tightly as possible in the sense of holding the oxygen absorbent. However, if it is desired to increase the permeability of oxygen or water vapor for the purpose of improving the oxygen absorbing ability, a porous structure may be employed. The oxygen absorbing layer in which the oxygen absorbing agent is embedded in the silicone resin is formed by mixing the silicone compound and the oxygen absorbing agent, applying the mixture to a predetermined thickness on the substrate of the oxygen-permeable composite film, and then curing the mixture. It is possible. The coating method is not particularly limited, but is applied by, for example, screen printing or the like in a form suitable for the intended use. The thickness of the coating cannot be determined unequivocally because the required amount of oxygen absorbent varies depending on the amount of oxygen inside the bag, but if there is an oxygen barrier film layer, the adhesiveness with the oxygen barrier film layer and the oxygen barrier property In consideration of the hermeticity of the film layer, it is preferably between 5 μm and 3 mm. In addition, it is possible to dilute the mixture of the compound and the oxygen absorbent with a solvent to facilitate application. Solvents such as hexane, cyclohexane, freon, ether, and halogenated hydrocarbons having a low boiling point and being volatile can be suitably used in the sense of maintaining the form after coating, but are not particularly limited thereto. Absent. The volume ratio between the embedding resin and the oxygen absorbent is not particularly limited, but the absorbent / resin = 0.2 to
2.0 is a preferred example. However, in consideration of the oxygen absorbing ability and the retention of the oxygen absorbent, 0.7 to 1.3 is particularly preferable.

(6) Oxygen Absorber Known oxygen absorbers can be used as they are.
For example, ascorbic acid, ascorbate, isoascorbic acid, isoascorbate, gallic acid, gallate, tocopherol, hydroquinone, catechol, resorcin, dibutylhydroxytoluene, dibutylhydroxyanisole, pyrogallol, Rongalit, sorbose, glucose, lignin Organic oxygen absorbers such as iron powder, activated iron, ferrous oxide, iron-based oxygen absorbers such as iron salts, sulfites, thiosulfates, dithionites, bisulfites and other inorganic oxygen absorbers One or a mixture of two or more selected from an oxygen absorbent such as an absorbent, a redox resin, a polymer metal complex such as a polymer metal complex, and a zeolite or activated carbon is appropriately used according to use conditions. When the oxygen absorbent is in the form of powder, the particle size thereof is not particularly limited, but is generally preferably small in terms of increasing the surface area. The oxygen absorbent may contain other substances such as a catalyst, a water retention agent, and a hydrate to control the oxygen absorbing ability. As the oxygen absorbent, those which do not exhibit oxygen absorbing ability under a normal atmosphere (room temperature, 70% or less relative humidity) and exhibit oxygen absorbing ability near a dew point can be easily manufactured and stored in the laminate of the present invention. It has the advantage of being particularly preferred, but is not limited to this.

(7) Oxygen Barrier Film Layer The oxygen barrier film layer is a layer whose main purpose is to shield the contents of the bag and the oxygen absorber from outside air. Generally, polyvinylidene chloride-coated KOP (registered trademark) / PE (K-coated polypropylene / polyethylene), KON (registered trademark) /
PE (K coated nylon / polyethylene), KPET
(Registered trademark) / PE (K-coated polyester / polyethylene), films such as EVAL (registered trademark), Saranex (registered trademark), OV (registered trademark), Varilon (registered trademark), aluminum foil / polyethylene, etc. ° C
Permeation rate of 1.0 [ml / m ² · hr · at
m] The following may be mentioned, but when the oxygen absorbent has low activity under low humidity or when the time from production to mounting is short, it is not always necessary to satisfy this condition. Specifically, the oxygen transmission rate at 20 to 25 ° C. is 4000 [ml
/ M ² · hr · atm] or less, but there is no particular limitation, but when an oxygen absorbent commonly called a fast-acting type is used, the oxygen permeation rate is 125 [ml / m ² · hr · a
tm] or less. The thickness of the oxygen barrier film layer is preferably 800 μm or less in consideration of the adhesion to the oxygen-permeable composite film, and is preferably 50 μm or more in consideration of the mechanical strength. In particular, in consideration of workability as a packaging bag, the thickness is more preferably 0.5 to 50 μm.

(8) Sealing Film In the case of a packaging bag, no matter how much an oxygen barrier film is used, if the sealing performance of the bag to be sealed is poor, air enters from the bag and the contents are oxidized and deteriorated. Resulting in. In the packaging bag of the present invention, the asymmetric porous layer side of the oxygen permeable layer is sealed. Therefore, it is preferable that a heat-sealable film such as polyethylene or polypropylene be laminated at least on the sealing portion to keep the airtightness of the packaging bag. However, the sealing film is not limited to the heat sealing property, and can be appropriately selected depending on the purpose, such as an adhesive film.

[0033]

Embodiments of the present invention will be described below. The performance of the oxygen permeable composite membrane is as follows: the primary side pressure is 2 kg / cm ² , the secondary side pressure is 1 kg / cm ² , and the gas (oxygen or nitrogen) permeation rate is a precision membrane flow meter across the composite membrane. S
It was measured by F-101 (manufactured by Standard Technology). The oxygen transmission rate Q _O2 is expressed in units of [m ³ / m ² ·
[hr · atm] and used as an index of gas permeability of the oxygen-permeable composite membrane. The oxygen / nitrogen transmission rate ratio α of the oxygen-permeable composite membrane was calculated from Q _O2 / Q _N2 and used as an evaluation standard for the homogeneity of the polymer thin film layer contained in the composite membrane.
In addition, the inherent oxygen /
The nitrogen transmission speed ratio α ^* (= P _O2 / P _N2 ) and the oxygen transmission coefficient P _O2 were measured by a depressurization method at 25 ° C. using a dense film of a raw material polymer by a gas permeability measuring device manufactured by Yanagimoto Seisakusho.

Example 1 An oxygen-permeable composite membrane (A) having oxygen permeability was prepared by the following method. A 15% by weight dimethylformamide (DMF) solution of polysulfone (Udel-P3500 manufactured by Union Carbide Co., Ltd.) was coated on a polyester nonwoven fabric (MF110 manufactured by Nippon Vilene Co., Ltd.) having a thickness of 50 μm and a basis weight of 100 g / m ² at room temperature. The polysulfone is coagulated by casting and dipping in a coagulation bath filled with water to form a membrane (I) comprising a 200 μm thick polysulfone porous layer (75% porosity) / polyester nonwoven fabric (130 μm thickness). Obtained. 0.2% by weight silanol polydimethylsiloxane at both ends (number average molecular weight 30,000 to 50,000),
A 0.1% by weight solution of tetrakis (2-propanone oxime) silane in trichlorotrifluoroethane was coated on the drained membrane (I) only at 130 ° C.
After drying by heating for 2 seconds, drying was performed at 100 ° C. for 10 minutes to obtain an oxygen-permeable composite membrane (A) composed of a crosslinked siloxane homogeneous thin film layer (thickness: about 0.1 μm) / polysulfone porous layer / polyester nonwoven fabric. The oxygen transmission rate Q _O2 of this oxygen permeable composite membrane is 6 [m ³ / m ² · hr · atm], the oxygen / nitrogen transmission rate ratio α (= Q _O2 / Q _N2 ) is 2.0, and the water vapor transmission rate is 15 [m ³ / m ² · hr · atm]. The specific oxygen / nitrogen transmission rate ratio α ^* of the crosslinked siloxane forming the thin film layer is 2.0 (the oxygen transmission coefficient P _O2 is 5 × 10 ^−8).
cm ³ · cm / cm ² · sec · cmHg), and it was confirmed that a uniform thin film layer having no defect was formed.

Under a nitrogen stream, an iron-based oxygen absorbent (Ageless (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd.) is used as an oxygen absorbent.
FX type inclusions (2.5 g), and one-component curing type RTV silicone (KE44 manufactured by Shin-Etsu Chemical Co., Ltd.)
After adding 2.0 g to cyclohexane and mixing well,
The mixture was applied to the surface of the polyester nonwoven fabric of the oxygen-permeable composite membrane (A) at a rate of 0.07 g / cm ² and dried. On top of this, a stretched polypropylene / evar / polyethylene (20/17) was used as an oxygen barrier film layer.
/ 60 μm) The sheet was heat-pressed at 140 ° C. for 10 minutes on the side of the surface coated with the oxygen absorbent to be fixed. As shown in FIG. 1, the laminate sheet obtained in this manner has an asymmetric porous film comprising an oxygen-permeable homogeneous thin film layer 3, a dense layer 4 and a porous layer 5 from the bag inner side 1 to the outer side 2. It has a laminated structure of a porous layer 6, a support layer 7 made of a polyester nonwoven fabric, an oxygen absorber layer 8 in which an oxygen absorbent is embedded, and an oxygen barrier film layer 9. As shown in FIG. 2, the oxygen-absorbing laminated sheet 10 can be an oxygen-absorbing laminated sheet 11 without the oxygen-permeable homogeneous thin film layer 3. Further, as shown in FIG. 3, on the oxygen-permeable homogeneous thin film layer 3 of the oxygen-absorbing laminate sheet 10, a sealing film layer 12 is provided at a necessary portion in order to secure a sealing property at the time of bag making. It is preferable to provide the laminated sheet 13 provided. The sealing film layer 12 is formed, for example, by heating and pressing a polyethylene sheet having a width of about 1 μm and a thickness of about 100 μm at 140 ° C. for 10 minutes, for example, at a necessary portion around the laminate sheet 10. In this embodiment, an oxygen-absorbing laminate sheet 13 as shown in FIG.
After accommodating potato chips as contents, the sealing film layers 12 were heat-sealed with each other. After the packaging bag was stored for 6 months under normal temperature and normal pressure, the contents of potato chips were evaluated. As a result, no change in taste and flavor was observed.

Example 2 In Example 1, as an iron-based oxygen absorbent, Ageless (registered trademark) S type (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used.
An experiment was conducted in the same manner except that 5 g) was used. As a result, no change in the taste and flavor of the potato chips was observed even after storage for 6 months.

Example 3 Polysulfone (Udel- manufactured by Union Carbide Co., Ltd.)
P3500) 15% by weight dimethylformamide (DM
F) Non-woven fabric made of polyester fiber at room temperature with a thickness of 50 μm (MF-11, manufactured by Japan Vilene Co., Ltd.)
0) Cast on top and immerse in a coagulation bath filled with water to coagulate the polysulfone, and a membrane composed of a polysulfone porous layer (porosity: 75%) with a thickness of 160 μm / polyester nonwoven fabric (thickness: 130 μm) (II) was obtained.
An amino-modified polydimethylsiloxane having the structure shown below was dissolved in trichlorotrifluoroethane to prepare a 2% by weight polymer solution.

[0038]

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Separately, a 1% by weight solution of tolylene diisocyanate / dibutyltin diacetate [= 9/1 (weight ratio)] in trichlorotrifluoroethane was prepared. After mixing the two liquids at a ratio of 1: 1, the mixture was further diluted with trichlorotrifluoroethane to prepare a dilute solution. A part of the diluted solution is coated on the drained membrane (II), dried by heating at 130 ° C. for 1 minute, and then dried at room temperature for 1 hour to form a crosslinked siloxane homogeneous thin film layer (thickness: about 0.08 μm). / Polysulfone porous layer /
An oxygen-permeable composite membrane (B) made of a polyester nonwoven fabric was obtained. The oxygen permeable composite membrane has an oxygen permeation rate Q _O2 of 10
[M ³ / m ² · hr · atm], the oxygen / nitrogen transmission rate ratio α (= Q _O2 / Q _N2 ) is 2.1, and the water vapor transmission rate is 21 [m ³ / m ² · hr · atm]. Met. The specific oxygen / nitrogen transmission rate ratio α ^* of the crosslinked siloxane forming the thin film layer is 2.1 (the oxygen transmission coefficient P _O2 is 6 × 10 −8 c
m ³ · cm / cm ² · sec · cmHg), and it was confirmed that a uniform thin film layer having no defect was formed.

Except for using the oxygen-permeable composite membrane (B),
When a packaging bag using the laminate of the present invention was prepared and evaluated in the same manner as in Example 1, the taste and flavor of the potato chips were not reduced even after storage for 6 months.

Example 4 Poly (4-methylpentene-1) (TPX manufactured by Mitsui Petrochemical Industry Co., Ltd.) was added to 250 g of anhydrous xylene under a nitrogen atmosphere.
RMX-001) was heated and dissolved in 25 g, and 50 g of trimethoxyvinylsilane was added. Then, 1.25 g of benzoyl peroxide was added, followed by a reaction at 110 ° C. for about 4 hours. After purifying the obtained polymer by repeating reprecipitation twice from methanol, vacuum drying is performed and methoxysilane graft poly (4-methylpentene-1) is obtained.
I got The silicon content of this graft polymer is between 0.
13%. 1 g of the synthesized methoxysilane-grafted poly (4-methylpentene-1) and di-n-laurate
-Butyltin (10 mg) was dissolved in 200 g of cyclohexane. This solution was prepared using the membrane (I) prepared in Example 3.
I) Coating on top, drying by heating at 140 ° C. for 5 minutes, drying at room temperature for 1 hour, cross-linked poly (4-methylpentene-1) homogeneous thin film layer (thickness: about 0.1 μm) / polysulfone porous layer / Oxygen-permeable composite membrane (C) composed of polyester nonwoven fabric was obtained. The oxygen transmission rate Q _O2 of this oxygen permeable composite membrane is 0.2 [m ³ / m ² · hr · atm], and the oxygen / nitrogen transmission rate ratio α (= Q _O2 / Q _N2 ) is 3.
8. The water vapor transmission rate is 5 [m ³ / m ² · hr · atm]
Met. The specific oxygen / nitrogen transmission rate ratio α ^* of the crosslinked siloxane forming the thin film layer is 4.2 (the oxygen transmission coefficient P _O2 is 1.5 × 10 ⁻⁹ cm ³ · cm / cm ² · sec ·
cmHg), and it was confirmed that a uniform thin film layer having no defect was formed.

Except for using the oxygen-permeable composite membrane (C),
When a packaging bag using the laminate of the present invention was prepared and evaluated in the same manner as in Example 1, the taste and flavor of the potato chips were not reduced even after storage for 6 months.

[0043]

The packaging bag using the oxygen-absorbing laminate sheet of the present invention has the following effects on preservation of those that are deteriorated or deteriorated by oxygen. (1) Since an oxygen absorber having a high oxygen absorption rate and capable of keeping the activity of the oxygen absorbent sufficiently high until the time of wearing is used, the content of the packaging bag has a high freshness retaining ability. (2) Sufficient shielding effect against liquids etc. can be exhibited while ensuring high oxygen permeation performance, so there is no permeation of liquids etc. into the oxygen absorber, and long-term use is possible even when applied to liquids and water-containing substances. It is. (3) Since there is no permeation of a liquid or the like into the oxygen absorber, phenomena such as a chemical reaction and generation of an unusual odor due to the reaction between the oxygen absorbent and the liquid do not occur. (4) Since there is an oxygen barrier film layer, intrusion of oxygen from the outside of the bag can be efficiently suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an oxygen-absorbing laminate sheet for producing a packaging bag according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of an oxygen-absorbing laminate sheet for producing a packaging bag according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of an oxygen-absorbing laminate sheet for producing a packaging bag according to still another embodiment of the present invention.

[Explanation of symbols]

 1 Inside of bag 2 Outside of bag 3 Oxygen-permeable homogeneous thin film layer 4 Dense thin film layer 5 Porous layer 6 Asymmetric porous layer 7 Support layer 8 Oxygen absorber layer 9 Oxygen barrier film layer 10, 11, 13 Oxygen absorption Laminated sheet 12 Sealable film layer

Continuation of the front page (56) References JP-A-55-107465 (JP, A) JP-A-63-264123 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65D 81 / 26 B32B 27/18

Claims (3)

(57) [Claims] At least a part of a bag is provided with an oxygen absorber layer in which an oxygen absorbent is embedded in a resin, and a dense thin film layer located on the bag inner side of the oxygen absorber layer in the thickness direction of the bag. A packaging bag comprising: a laminate comprising an oxygen-permeable layer having an asymmetric porous layer formed with a layer, and an oxygen-barrier film layer located on the outside of the bag with respect to the oxygen absorber layer. 2. The packaging bag according to claim 1, wherein the oxygen-permeable layer comprises the asymmetric porous layer and a support layer that supports the asymmetric porous layer and is made of any one of a woven fabric and a nonwoven fabric. . 3. The laminate according to claim 1, further comprising an oxygen-permeable homogeneous thin film layer inside the oxygen-permeable layer inside the bag.
Or the packaging bag of 2.